Law professor: The government will 'fail' in the Article 50 Supreme Court case

Gina Miller, the lead claimant in the case against the UK government. Bloomberg The Supreme Court will rule next month whether Theresa May must secure parliamentary approval before invoking Article 50 and taking the UK out of the European Union.

However, the government opted to appeal the verdict, meaning the case will be revisited by the UK's most powerful court on December 5-8. It'll be the first time that the court has sat in full since its creation in 2009.

The stakes could not be higher. If the government's appeal is upheld, May will be able to invoke Article 50 without first passing an act of parliament. However, the High Court's ruling against the government was unanimous, which suggests its lawyers face an almighty task in persuading the Supreme Court to reverse the historic decision.

Business Insider interviewed Trevor Tayleur, Associate Professor at the University of Law and former solicitor, to get his expert take on the key issues heading into next month's case and who he expects to win.

Business Insider's Adam Payne:Are you surprised that the government decided to appeal the High Court ruling given the judges reached a unanimous verdict?

Trevor Tayleur: "No, I wasn't that surprised. I think they indicated beforehand that they would and the fact that the judgment takes place in January means the appeal doesn't jeopardise their target of triggering Article 50 in March. If they did need an act of parliament they could probably get it through by the end of March."

BI: Who do you think will win?

Tayleur: "I think the odds are against the government — but that's by no means a dead certainty.

"I've heard people say that the government didn't argue its case particularly well in the High Court and there were certain arguments that they could have put forward better which they didn't. There are blogs by authoritative academics who are arguing that the High Court decision was wrong.

"The High Court judgment was well-reasoned, it was unanimous, and was in a very powerful court"

"But, on the other hand, the High Court judgment was well-reasoned, it was unanimous, and was in a very powerful court which included the Lord Chief Justice and the Master of the Rolls, who normally sit in the Court of Appeal but due to the importance of the case sat in the High Court.

"I think the appeal will fail."

BI: What are the main arguments at the centre of this appeal?

Tayleur: "One of the big things on the appeal is going to be on whether the Article 50 notice is revocable or not.

"Both sides accepted that it was not revocable [in the High Court case] but there are suggestions that the issue could be revisited by the Supreme Court and if the notice is revocable then it could lead to a different outcome.

"The reason being is that one of the arguments in the High Court for the claimants was that the Article 5o notice has been invoked all the rights granted under the European Communities Act would inevitably come to an end on the expiry of the notice. But if it is revocable then that isn't necessarily the case because it wouldn't be inevitable that these rights would end in two years' time."

BI: Is it Supreme Court likely to raise the issue of Article 50's revocability?

Tayleur: "I think the Supreme Court would allow the issue to be re-opened because it's such fundamental issue.

"Also, whether Article 50 is revocable or not is a question of EU law and the UK court is required to take notice of issues of EU law even if not raised by the involved parties. I think it's very likely that the Supreme Court would be willing to consider it in its motion or if asked by the government."

BI: There has been talk of this case eventually reaching the European Court of Justice (ECJ) — the European Union's highest court — is this a realistic scenario?

Tayleur: "Where questions of EU law arise in a case and they are critical to the outcome then UK courts are required refer that question to the European Court of Justice. With the Supreme Court being the highest court in the country, if a question of EU law arises that's critical to the outcome, then its duty would be to refer it to the ECJ and whether Article 50 is revocable or not is a case of EU law.

"But it all depends on how critical the revocability or otherwise of the Article 50 notice is deemed to be to the Supreme Court's judgment."

BI: What is Scotland's role in this case?

Tayleur: "It was argued in the Northern Ireland case that royal prerogative had been curtailed by legislation relating to setting up of the Northern Irish assembly and the agreement between the north and the south. In the Scottish case, what they would try and argue is that devolution legislation has removed royal prerogative power in relation to Scotland and the Article 50 notice. That argument was rejected in the case of Northern Ireland although the legislation in Scotland is different.

"The other issue relates to whether the Westminster parliament can pass an act to take the UK as a whole out of the EU without the consent of the Scottish Parliament. There's something called the Sewel Convention — named after Lord Sewel who was a Scottish minister at the time — that says Westminster will not legislate on devolved matters without the consent of Scottish parliament and that now appears in the Scotland Act 2016. The argument is that the Scottish parliament is under a duty to observe EU law and if the UK leaves the EU it will directly affect Scottish parliament."